Automated high-performance liquid chromatographic assay for the determination of 7-ethoxycoumarin and umbelliferone

The Development of a Novel Therapeutic Strategy to Target Hyaluronan in the Extracellular Matrix of Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal diseases to affect humans, regardless of whether patients receive multimodal therapy (including surgery, radiotherapy, and chemotherapy). This resistance to intervention is currently considered to be caused by the desmoplastic change of the extracellular matrix (ECM) in PDAC tissues, which is characterized by the accumulation of cancer-associated fibroblasts, collagen, proteoglycan, and hyaluronan. Among these ECM components, hyaluronan has attracted interest because various studies have indicated that hyaluronan-rich PDAC is correlated with the progressive properties of cancer cells, both in experimental and clinical settings. Hence, the reduction of hyaluronan in cancer tissue may represent a novel therapeutic approach for PDAC. 4-methylumbelliferone (4-MU) is a derivative of coumarin that was reported to suppress the synthesis of hyaluronan in cultured human skin fibroblasts in 1995. As an additional study, our group firstly reported that 4-MU reduced the hyaluronan synthesis of mouse melanoma cells and exerted anti-cancer activity. Subsequently, we have showed that 4-MU inhibited liver metastasis in mice inoculated with human pancreatic cancer cells. Thereafter, 4-MU has been accepted as an effective agent for hyaluronan research and is expected to have clinical applications. This review provides an overview of the interaction between PDAC and hyaluronan, the properties of 4-MU as a suppressor of the synthesis of hyaluronan, and the perspectives of PDAC treatment targeting hyaluronan.

Inhibitory effects of nicardipine to cytochrome P450 (CYP) in human liver microsomes

To anticipate drug-drug interactions by nicardipine in vivo, cytochrome P450 (CYP) forms responsible for the metabolism of nicardipine and inhibition of CYP-dependent drug metabolism by nicardipine were investigated. Microsomes of human B-lymphoblastoid cells expressing each human CYP form were used for the metabolism of nicardipine. Inhibitory effects of nicardipine on drug metabolism were studied using human liver microsomes. CYP2C8, CYP2D6 and CYP3A4 were identified as major CYP forms for the metabolism of nicardipine in human liver microsomes. Nicardipine strongly inhibited two-pathways of triazolam hydroxylation both catalyzed by CYP3A4. Comparison of three Ca(2+) antagonists, nicardipine, nifedipine, and diltiazem revealed that only nicardipine showed such a strong inhibitory potency on the typical CYP2D6-catalyzed drug metabolism. Furthermore, nicardipine inhibited other reactions catalyzed by CYP1A, CYP2A6, CYP2C8, CYP2C9 and CYP2C19 with K(i) values ranging from 1.1 to 29.4 microM. In conclusion, nicardipine was a relatively potent inhibitor of human CYP2D6, CYP3A4 and CYP2C (especially for CYP2C8 and CYP2C19) in vitro, suggesting that drug-drug interactions between nicardipine and other drugs metabolized mainly by these CYP forms appear to occur in vivo.

Inhibition of angiogenesis by thalidomide requires metabolic activation, which is species-dependent

Thalidomide has been shown to be an inhibitor of angiogenesis in a rabbit cornea micropocket model; however, it has failed to demonstrate this activity in other models. These results suggest that the anti-angiogenic effects of thalidomide may only be observed following metabolic activation of the compound. This activation process may be species specific, similar to the teratogenic properties associated with thalidomide. Using a rat aorta model and human aortic endothelial cells, we co-incubated thalidomide in the presence of either human, rabbit, or rat liver microsomes. These experiments demonstrated that thalidomide inhibited microvessel formation from rat aortas and slowed human aortic endothelial cell proliferation in the presence of human or rabbit microsomes, but not in the presence of rat microsomes. In the absence of microsomes, thalidomide had no effect on either microvessel formation or cell proliferation, thus demonstrating that a metabolite of thalidomide is responsible for its anti-angiogenic effects and that this metabolite can be formed in both humans and rabbits, but not in rodents.